"Essential PHP Security" is an essential book for experienced PHP programmer. It discusses essential security measures you can take for making your PHP applications secure. Even if there are another team for your high profile web site's security then also it is very useful. You will learn about many php.ini configurations and good programming practices like always initializing your variables. This book will tell about the security concerns PHP blamed for. This book speaks about why register_globals should be Off.
"Essential PHP Security" will teach you terms in web security like Cross-Site Scripting, Brute Force Attacks, password sniffing, Cross-Site Request Forgeries, SQL Injection and others. This book is small but complete in itself written by Shiflett.